A popular strategy used in recently or the Kalahari finals was to have one defensive robot on each alliance zoning/ defending the attacking one. What are some really good tricks, manoeuvres to defeat this type of strategy (both from the defenders and attackers perspective?)

I’m probably not the best qualified to answer this but here goes

The same strategy was actually also used heavily during the Australian National Championships- the most common counter strategy was to essentially do the same to the other team

That being said, there are other ways to counter this. If you can shoot discs well / fast, then it is a pretty good idea just to simply get as far away from the defending robot as possible, quickly launch three discs and then run again.
Often, it’s possible to outmaneuver them such that the low goal barrier is between you and them, meaning they have to drive around it. So essentially just position your robot to be as far away as possible from the defending robot.
You can also shoot from the low goal entrance, so they can only push you against the wall or forwards or backwards- this limits their defensive options because they can’t push you much when you’re already in a small space so to speak.